Mitochondrial phosphoenolpyruvate carboxykinase (PCK2) regulates metabolic adaptation and glucose-independent tumor cell growth. Homo sapiens

Cancer cells must adapt metabolically to survive and proliferate when nutrients are limiting. Here we used combined transcriptional-metabolomic network analysis to identify metabolic pathways that support glucose-independent tumor cell growth. We found that glucose deprivation stimulated the re-wiring of the tricarboxylic acid (TCA) cycle and co-opting early steps of gluconeogenesis to promote cell proliferation under low glucose. Glucose limitation promoted the production of phosphoenolpyruvate (PEP) from glutamine, which was used to fuel biosynthetic pathways normally sustained by glucose, including serine and purine biosynthesis. Mitochondrial PEP-carboxykinase (PCK2) was required for this glutamine-dependent metabolic reprogramming. PCK2 expression was dependent on the hypoxia-inducible factors (HIFs), and required to maintain tumor cell proliferation under limiting glucose availability. Elevated PCK2 expression is observed in several human tumor types, and enriched in tumor tissue from non-small cell lung cancer (NSCLC) patients. Our results define a novel role for PCK2 in cancer cell metabolic reprogramming that promotes glucose-independent cell growth and metabolic stress resistance in human tumors. Overall design: A549 cell line was obtained from ATCC (Manassas, VA, USA). A549 cells were cultured in the presence (25 mM) or absence of glucose for 48 hours prior to RNA extraction.